Sorry, but no, it is not. At the very least, you must have an estimate of runoff (Q, discharge) to close the water budget and solve for storage (dS, recharge).
dS = P - ET - Q (+/- error)
You will be limited by the precision of the measurements you have -- it is very likely that the error term may be greater than the value of dS, making your estimate pretty much useless. You are also limited by the fact that a spatially-homogenized national estimate does not spatially align with a watershed basin. You are better off making estimates for each major basin in the country you are studying. Good Luck.
It depends on the geographical position of your country. But as a whole, you need the runoff data to calculate the ground water recharge data. In a local scale you may calculate the recharge by studying the grain size (which is mainly responsible to give a passage to flow the surface water to ground). Clay content plays the exactly opposite role as sand. Clay doesn't favour penetration water to ground. In that case you may calculate the recharge with the help of precipitation and evapotranspiration. Runoff doesn't play a major role in the recharge of ground water. But in case of other components you need run off data and the formula dS = P - ET - Q to calculate recharge of ground water.
Ok, it won't be that easy, but, as a first approach, you may identify the main parametters of a given aquifer system: nature of the outcropping layers for infiltration, nature of the surface for the runoff, variation of the watertable if possible... the least you can start with is to fech in the liiterature similar areas, with comparable factors and see how it would match with yours...
@Hamd Ben Dhia, I am also agree with your answer. In a larger spatial scale (national) it is next to impossible to evaluate the ground water recharge. I want to know is there any technology available to decipher the relationship among precipitation, evapotranspiration and ground water recharge. In a country like India, you only get the runoff data from the major rivers ( if your luck is good enough to contact and get the data). In that situation you will never infer the actual ground water recharge which is the major challenge in bigger cities inside Indian subcontinent.
The nature of soil is a critical variable, that is impossible to give national level scale for.
Dear Sarthak
I guess that you have to launch a first study with a minimum of information about geology, wells inventory and water levels, potential relation between rivers and shallow aquifers, some data about the flows of rivers and a potential relation with raifall events... It is worth to be undertaken, as a dedicated program. Good luck
Nosotros utilizamos un balance diario de la relación de las precipitaciones utilizando un modelo matemático basado en el Esquema del Método de la Curva Numero (USDA CN Method) , que permite estimar el escurrimiento superficial en función de las características de los suelos, el uso del territorio. Y por otra parte estimar las perdidas por evapotranspiración a partir de datos climáticos y de cultivos.
Finalmente de este balance vertical, precipitación, escurrimiento e infiltración podemos estimar las variaciones de almacenamiento en el suelo. EL Aporte como ecarga del acuífero surge como el exceso de agua gravífica.
Net GW recharge = P - ET may be plausible in a small depressional area where there is no surface runoff leaving the area ( like a bowl shaped valley). However, unless an entire nation falls within such a topography (and I do not know of any such nation! ), the error involved by neglecting runoff would be very high, probably rendering any such estimate meaningless, as pointed out by the others.
El Método de la Curva Número del Servicio de Conservación de suelos de los Estados Unidos fue diseñado para estimar escurrimiento a partir de eventos de precipitación, potencial de escurrimiento del suelo y uso de la tierra, por lo que tiene la capacidad, basado en un equilibrio de masas de estimar mediante un Balance Hídrico la infiltración para dicho evento, lo que es almacenado en el perfil del suelo y mediante el proceso de evapotranspiración vuelve a la atmósfera.
El exceso de agua capilar pasa a constituir lo que se conoce como agua gravífica y es la que recarga el o los acuíferos. A mayor escala los errores disminuyen.
Hi Dr. Tesfaye,
In some point you can calculate it using GIS (combination of vectorial data and raster calculations), and estimating average values based on a regionalization (boundaries of states, prefectures, watersheds). However, the result will be highly generalized, so in my perspective it will not be useful.
Best regards
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